Metal bonded grinding wheels

ABSTRACT

Grinding wheels having an electrodeposited metal matrix and abrasive grit forming a grinding surface, with an electrodeposited metal backing layer integrated with the composite matrix and grit layer; the matrix layer having an optimized distribution of grit therein.

Mar. 5, 1974 METAL BONDED GRlNDlNG WHEELS Inventor: Shirley l. Weiss,Ramsey, NL

[22] Filed: June 10, 1969 211 App]. No: 831,943

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51/293 Seligman et al. 51/309 11 Claims, 6 Drawing Figures PATENTEDHAR5W 3.795.491

10B 13B 14B\% FIG.4 11B w INVENTOR.

Shirley I. Weiss BY m w ATTORNEY I METAL BONDED GRINDING WHEELSBACKGROUND OF THE INVENTION Grinding wheel s, cutoff wheels and formingwheels having a grit-matrix grinding surface, have heretofore shownrather limited useful life; being operable with a rather reduced loadrelative to the materials being cut or ground; a tendency to rapid wearat the edges of the I device which necessitates repeated dressing of the.de-

' wheels. However, the reduced matrix proportion leads to inefficientgrit bonding and a resultant reduction in the useful life of the wheel,as well as poor grinding qualities.

Accordingly, an object of this invention is to provide improved grindingwheels, cutoff wheels, forming wheels and the like; having a grindingsurface made up of grit such as diamond particles held in anelectroplatedmetal matrix; wherein the concentration of grit isincreased substantially and may be of the order of 75 percent to 85percent of the total volume of the composite grit-matrix.

Another object of this invention is to provide improved grinding wheelshaving a grindingsurface made up of an electroplated metal matrixholding a very large proportion of diamond particles; the useful life ofsuch improved grinding wheels being extended by as much as 2 to timesthat of known grinding wheels.

Yet another object of this invention is to provide grinding wheels ofthe character described, wherein the total amount of grit particlesdistributed in an electroplated metal matrix of reduced radial dimensionto thereby substantially increase the concentration of particles in thematrix, thereby allowing a reduced amount of particles to be ofincreased effectiveness in use and reducing the cost of the device.

. Still another object of this inventionis to provide improved grindingwheels of the character described, wherein the distribution andconcentration of abrasive grit in an electroplated metal matrix is of acharacter to substantially reduce wear at the edges of the wheel andthereby reduce the need for dressing operations during the useful lifeof the wheel.

7 Yet another object of this invention is to provide improved grindingwheels of the character described, which are adapted to withstandincreased grinding loads when grinding or cutting very hard materials,thus realizing relatively high rates of material removal.

Other objects of this invention will in part be obvious and in parthereinafter pointed out.

DESCRIPTION OF THE DRAWING FIG. 1 is a transverse sectional view of agrinding wheel embodying the invention;

FIG. 2' is a sectional view taken on the line 22 of showing a cutoffwheel embodying the invention;

FIG. 4 is a sectional view similar to that of FIG. 3, showing a formingtool embodying the invention;

FIG. 5 is an elevational view in section showing apparatus for formingthe devices of the instant invention; and

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. I, 2; I0designates a-grinding wheel embodying the invention. The same comprisesa metal core II which may be formed of brass, aluminum, steel or thelike. The core 11 has affixed to the outer cylindrical surface thereof agrinding assembly 12 which comprises an outer annular layer 13 and abacking layer I4 integrated therewith.

The annular layer I3 is made up of an electroplated matrix of metal ormetal alloy carrying abrasive grit such as diamond particles or thelike. The grit content of the matrix is of the order of from about 40percent to about percent by volume. The backing layer 14 is anelectrodeposited layer of metal or metal alloy, preferably similar tothat of the matrix layer 13; the layers I3, I4 being in integratedrelation to each other.

Thus, the metal of layers I3, I4 may be of nickel, copper, silver;nickel-cobalt; copper-nickel; coppertin-nickel-cobalt, or other suitablemetals and metal alloys which lend themselves to electrodeposition. Thegrit size can vary in accordance with the desired grinding, cutting orforming characteristics of the wheel, as related to the character andhardness of the material being ground or cut; and may be in the range offrom 1 micron to l,200 microns. The radial thickness of layer I3 may beof the order of from about 0.010 inch to about 0.250 inch, while thethickness of layer 14 may range from about 0.050 inchto about 0.500inch.

Alternatively, the invention may be embodied in -a cutoff wheel 10A,shown in FIG. 3, wherein a metal core IIA carries the grinding assembly12A, made up of a composite metal matrix and grit layer 13A and abackinglayer of electrodeposited metal MA, as previously described.

Also, as shown in FIG. 4, the invention is embodied in a forming wheelor tool IIIB, with a core 11B carrying the grinding grit-matrix layer138 and backing layer 14B. Here the grinding layer ISB is contoured to aselected cross section corresponding to the section of the work piece tobe ground and formed.

The assembly I2, I2A or 128 is formed in apparatus shown in FIG. 5 andgenerally indicated at I5. Such apparatus comprises a pair of circulardisc members I6, I7 formed of methyl methacrylate or other suitablesynthetic resin. Disc I6 is formed on one surface thereof with anannular shallow recess 18, providing a shoulder I9. Disc 17 is formed onone surface thereof with a small diameter recess 20 and a concentriclarger diameter recess 21; an annular juncture portion 22 of conicalshape; and providing an annular shoulder 23.

The discs I6, I7 are held in axially opposed relation, with recesses I8,20 thereof facing each other; by a series of circumferentially spacedbolts 24 passing through aligned openings in the peripheral portions 25,26 respectively of said discs 16, I7.

assembly 123 made up of composit A tubular member 27 of a diameter tofit the same snugly in shoulders 19, 23 of discs 16,17, is disposedbetween said discs to form a rotatable plating chamber. Member 27 has anaxial extent equal to the axial extent of grinding wheel to be formed.An annular layer 28 of a low melting point alloy such as lead-tin or thelike, is cast on the inner surface-of member 27 and its annular innersurface 29 is precision machined to a given inner diamater.

A tubular anode 30 is axially mounted on disc 16 by way of a rod 31 anda nut 32 on its threaded inner end. The outer end portion of rod 31passes through an axial opening 33 in disc 16 and terminates in asocketed coupling head portion 34. A cathode connector 35 having athreaded portion 36 is screwed into the outer portion of disc 16 to makeelectrical contact with member 27 and layer 28.

A filler opening 37 is formed in disc 17, being closed by a threadedplug 38, to allow the plating chamber formed by assembled discs 16, 17and member 27, to receive a plating solution PS to a level above theanode 30. The solution PS typically may be of a nickel salt such asnickel sulfamate or the like, in which case the anode 30 is also ofnickel.

The solution PS also contains a calculated quantity of diamond or otherabrasive grit of selected size. The apparatus 15 is arranged forrotation about its horizontal axis, by suitable motor means, not shown,through coupling head 34. Leads from a suitable plating current sourceare connected to cathode connector 35 and anode rod 31, in a mannerknown in the art. The current source has a voltage of from 2 to 6 voltsand an amperage of the order of from 5 to 30 amperes per sq. ft.

' The apparatus 15 is operated in two successive phases. Initially, thedevice is alternatively rotated at a given constant speed and stopped;with the rotational periods ranging from 2 to 30 seconds and the restperiods ranging from 2 to 30 seconds. The rotational speed is of theorder of from about 0.25 to 5.0 rpm.

During such initial phase of operation, the composite layer 13 made upof metal or metal alloy and grit is electrodeposited on the innersurface29 of annular layer 28. Upon exhausting the diamond grit content ofsolution PS, the layer 13 is completed to a selected radial dimension.Such layer 13 may have a grit content of up to 75 percent to 85 percentby volume. Reduced volumetric proportions of grit, to values of about 40percent by volume may be attained by suitable adjustment .of therotational and rest periods of the initial phase of operation ofapparatus 15.

The apparatus 15 is then operated in its second phase, by rotating thedevice continuously at a rate of from about 0.25 to about 5.0 rpm, toform the backing layer 14 of metal or metal alloy in integrated relationto layer 13. The radial thickness of layer 14 may vary from 0.050 inchto 0.500 inch; and may be suitably related to the radial thickness oflayer 13.

The apparatus 15 is provided with a breather assembly 41 mounted on disc17; the same comprising a nipple 42 with an upstanding breather tube42A; the nipple 42 passing through an opening 43 in disc 17 with apacking 44 and gland nut 45 sealing the same. A stem 46 extending froman outer portion of nipple 42 anchoring the same as at 47 to maintaintube 42A in its upright position while the apparatus rotates. Thus,gases discharged in chamber 40 during the electrode- 4 positionoperation, may be evacuated by way of breather tube 42A and nipple 42.

When the electrodeposition operations have been completed, the remainingsolution PS is drained by way of opening 37 and the discs 16, 17 aredisassembled from the member 27. The member 27 is then subjected to atemperature sufficient to melt layer 28, permitting the assembly 12 tobe separated from member 27.

The composite 13, 14 of assembly 12 is now ready to be mounted on core11. To this end, the 1D. of assembly 12 is machined to a given value andthe CD. of core 1 1 is machined to a value slightly greater than that ofthe ID. of assembly 12. The core 11 is then cooled by dry ice, liquidnitrogen, or the like to temporarily reduce the 0D. to a value slightlyless then the 1D. of assembly 12, allowing insertion of core 11 inassembly 12. On regaining room temperature, the core 11 is in a grippingrelation to assembly 12, to form the finished grinding wheel 10.

It will be apparent that assembly 12 may be secured in mounted relationto core 11, as by soldering or brazing; or by an interlayer of epoxyresin adhesive.

It is understood that member 27 is replaced by other members whenforming the cutoff wheel 10A, in which case member 27 has a small axialextent of the order of the thickness of core 11A. Also, the member 27may be profiled at its periphery to provide an appropriate transversecontour in deposited layer 28, which in turn produces the composite 13B,14B, FIG. 4, of corresponding contour to form with core 118, formingtool 10B.

It will be apparent that plating solution PS is made up in a knownmanner, to include salts corresponding to the metal or alloy to bedeposited to form the matrix carrying the abrasive grit.

It has been found that the procedure hereinbefore disclosed, allows forthe layer 13 of the grinding assembly 12 to be made up of superposeddiamond or other abrasive particles with interposed metal matrixmaterial. Thus, the radial dimension of layer 13 is dependent on thenumber of superposed particles, particle size and proportion of metalmatrix.

I claim:

I 1. A grinding member comprising a core element and an abrasive layeron said core element, said abrasive layer comprising an electrodepositedouter stratum consisting of a metallic matrix and abrasive gritdistributed through said matrix and an electrodeposited inner stratum ofmetal integrally bonded to said outer straturn, said matrix having agrit content of from about 40 percent to about 85 percent by'volurne,said abrasive layer being in annular form and being in shrink fitrelation to said core element.

2. A grinding member as in claim 1 wherein said matrix has a gritcontent of from about percent to about percent by volume.

3. A grinding member as in claim 1 wherein said grit is diamondparticles.

4. A grinding member as in claim 3 wherein the metal of said matrix isselected from the group consisting of nickel, copper, silver, nickelalloys and copper alloys.

5. A grinding member as in claim 1, wherein the grit in said outerstratum comprises at least three superposed particles extending throughthe thickness thereof.

6. A grinding member as in claim 1, wherein said abrasive layer is ofprofiled cross section.

7. A grinding member as in claim 1 wherein, said outer stratum has aradial thickness of from about 0.010 inch to about 0.250 inch, and saidinner stratum has a radial thickness of from about 0.050 inch to about0.500 inch.

8. A method of forming a grinding layer for a grinding member comprisingproviding a rotatable electrolytic cell including an annular formingmember as the cathode element thereof andan anode element, with a metalplating solution containing a dispersion of abrasive grit in said cell,continuously applying plating current to said cathode and anode whilerotating said cell during successive spaced time intervals withintervening time intervals of non-rotation to electrodeposit a metallicmatrix carrying abrasive grit on said forming 11. A method as in claim8, wherein the alternating rotational and non-rotational time intervalsare from 2 to 30 seconds and the rotational speed is from 0.25 to 5.0rpm.

2. A grinding member as in claim 1 wherein said matrix has a gritcontent of from about 75 percent to about 85 percent by volume.
 3. Agrinding member as in claim 1 wherein said grit is diamond particles. 4.A grinding member as in claim 3 wherein the metal of said matrix isselected from the group consisting of nickel, copper, silver, nickelalloys and copper alloys.
 5. A grinding member as in claim 1, whereinthe grit in said outer stratum comprises at least three superposedparticles extending through the thickness thereof.
 6. A grinding memberas in claim 1, wherein said abrasive layer is of profiled cross section.7. A grinding member as in claim 1 wherein, said outer stratum has aradial thickness of from about 0.010 inch to about 0.250 inch, and saidinner stratum has a radial thickness of from about 0.050 inch to about0.500 inch.
 8. A method of forming a grinding layer for a grindingmember comprising providing a rotatable electrolytic cell including anannular forming member as the cathode element thereof and an anodeelement, with a metal plating solution containing a dispersion ofabrasive grit in said cell, continuously applying plating current tosaid cathode and anode while rotating said cell during successive spacedtime intervals with intervening time intervals of non-rotation toelectrodeposit a metallic matrix carrying abrasive grit on said formingmember, the metallic matrix having a grit content of from about 40percent to about 85 percent by volume thereof.
 9. A method as in claim8, and thereafter continuously rotating said cell to electrodeposite ametal backing layer in integrated relation to said grit carrying matrix,and separating the backed grit-carrying matrix from said forming member.10. A method as in claim 9, wherein said forming member is formed of alow melting point metallic material.
 11. A method as in claim 8, whereinthe alternating rotational and non-rotational time intervals are from 2to 30 seconds and the rotational speed is from 0.25 to 5.0 rpm.